Fuel injection device

Abstract

A fuel injection device includes a cylinder that defines a pressure chamber at an end portion of a nozzle needle. A floating plate as a control member is placed in the cylinder. A cutout portion and multiple grooves are formed in the floating plate. The cutout portion and the grooves causes a gap between a large-diameter inner circumferential surface and an outer circumferential surface to communicate with the pressure chamber. The cutout portion and the grooves reduce a contact surface portion between the cylinder and the floating plate and divide the contact surface portion into multiple island portions. As a result, it is possible to reduce the contact surface portion.

What is claimed is: 
     
       1. A fuel injection device for an internal combustion engine, comprising:
 a valve body having a passage for high-pressure fuel provided therein, and having a nozzle hole configured to inject the high-pressure fuel into a combustion chamber of the internal combustion engine at a tip of the valve body; 
 a valve member movable in the valve body in an axial direction of the valve body to interrupt and allow supply of the high-pressure fuel to the nozzle hole; 
 a housing member provided to face an end portion of the valve member, to define a pressure chamber for regulating a pressure of fuel acting on the valve member to control the movement of the valve member, the housing member having therein an inflow path for causing the high-pressure fuel to flow into the pressure chamber and an outflow path for causing the fuel to flow out of the pressure chamber; 
 a control member arranged in the pressure chamber and brought into or out of contact with the housing member, to interrupt and allow communication at least between the inflow path and the pressure chamber; and 
 a cylinder housing the control member such that the control member is movable in the axial direction, the cylinder comprising: a large-diameter inner circumferential surface opposed to an outer circumferential surface of the control member; a small-diameter inner circumferential surface having an inside diameter smaller than an outside diameter of the outer circumferential surface of the control member; and a stepped surface provided between the large-diameter inner circumferential surface and the small-diameter inner circumferential surface and opposed to an end face of the control member on a side of the pressure chamber, wherein 
 a plurality of grooves are provided in at least one of the end face of the control member and the stepped surface of the cylinder, to divide a contact surface portion between the end face and the stepped surface into a plurality of island portions. 
 
     
     
       2. The fuel injection device according to  claim 1 , wherein
 the grooves are provided in at least an area outside the small-diameter inner circumferential surface in a radial direction. 
 
     
     
       3. The fuel injection device according to  claim 1 , wherein
 the grooves include grooves causing a gap between the outer circumferential surface and the large-diameter inner circumferential surface to communicate with the pressure chamber. 
 
     
     
       4. The fuel injection device according to  claim 3 , wherein
 the grooves include a cutout portion that is provided in the control member to have a bow shape as viewed from the end face, and is open in the outer circumferential surface and the end face. 
 
     
     
       5. The fuel injection device according to  claim 4 , wherein
 the grooves include a plurality of the cutout portions. 
 
     
     
       6. The fuel injection device according to  claim 5 , wherein
 the grooves include two cutout portions extending in parallel with each other along a diameter of the control member. 
 
     
     
       7. The fuel injection device according to  claim 5 , wherein
 the grooves include a plurality of the cutout portions that are arranged to surround a periphery of the control member. 
 
     
     
       8. The fuel injection device according to  claim 7 , wherein
 the grooves include four cutout portions. 
 
     
     
       9. The fuel injection device according to  claim 4 , wherein
 each the cutout portion is a chamfered portion provided in the corner portion between the outer circumferential surface of the control member and the end face. 
 
     
     
       10. The fuel injection device according to  claim 4 , wherein
 the grooves further include thin grooves thinner than the cutout portion. 
 
     
     
       11. The fuel injection device according to  claim 1 , wherein
 the grooves include three or more grooves provided to divide the contact surface portion into three or more island portions. 
 
     
     
       12. The fuel injection device according to  claim 1 , wherein
 the grooves include grooves provided in the control member. 
 
     
     
       13. The fuel injection device according to  claim 1 , wherein
 the grooves include grooves provided in the cylinder. 
 
     
     
       14. The fuel injection device according to  claim 1 , wherein
 the outer circumferential surface includes a large-diameter outer circumferential surface opposed to the large-diameter inner circumferential surface, and a small-diameter outer circumferential surface positioned between the large-diameter outer circumferential surface and the stepped surface and surrounding the end face.